Retroreflective sheetings have the ability to redirect incident light towards its originating source. This ability has led to the wide-spread use of retroreflective sheetings on a variety of articles. There are essentially two types of retroreflective sheeting: beaded sheeting and cube-corner sheeting. Beaded sheeting employs a multitude of glass or ceramic microspheres to retroreflect incident light. Cube-corner sheeting, on the other hand, typically employs a multitude of rigid, interconnected, cube-corner elements to retroreflect incident light.
A specular reflective coating such as a metallic coating can be placed on the backside of the cube-corner elements to promote retroreflection. In addition to or in lieu of a metallic coating, a seal film can be applied to the backside of the cube-corner elements. The sealing film maintains an air interface at the backside of the cubes to enhance retroreflectivity.
Various sealing films suitable for use with flexible retroreflective sheeting have been described. See for example U.S. Pat. Nos. 5,784,197; 5,691,846; and 6,318,867.